Photoresist strip method for low-k dielectrics

Abstract

The present invention pertains to methods for removing unwanted material from a semiconductor wafer during wafer manufacturing. More specifically, the invention pertains to stripping photo-resist material and removing etch-related residues from a semiconductor wafer. Methods involve implementing a plasma operation using hydrogen and a weak oxidizing agent, such as carbon dioxide. The invention is effective at stripping photo-resist and removing residues from low-k dielectric material used in Damascene devices.

Description

BACKGROUND[0001]The present invention pertains to methods for stripping photo-resist material and removing etch-related residues from the surface of a partially fabricated integrated circuit in preparation for further processing. More specifically, the invention pertains to methods for implementing a plasma operation using hydrogen and a weak oxidizing agent such as carbon dioxide. The invention is effective at efficiently stripping photo-resist and removing residues from low-k dielectric layers after etching processes used in Damascene devices.[0002]Damascene processing techniques are often preferred methods in many modern integrated circuit manufacturing schemes because it requires fewer processing steps and offers a higher yield than other methods. Damascene processing involves forming metal conductors on integrated circuits by forming inlaid metal lines in trenches and vias in a dielectric layer (inter-metal dielectric). As part of the Damascene process, a layer of photoresist i...

AI Technical Summary

Benefits of technology

The present invention provides improved methods for removing photoresist and etch-related residues from dielectric materials. The methods involve using a weak oxidizing agent, such as carbon dioxide or nitrous oxide, in a reaction chamber and applying RF power to form a plasma to convert at least a portion of the material to gaseous form, thereby removing at least a portion of the material from the partially fabricated integrated circuit. The methods can be used on both non-porous and porous dielectric materials, and can be performed on both small and large wafers. After applying RF power, the partially fabricated integrated circuit is then removed from the reaction chamber and a cleaning process is performed to remove any remaining material from the dielectric layer. The wet cleaning process typically involves exposing the partially fabricated integrated circuit to an acidic or basic solution, or deionized water, and can also involve using organic solvents. The technical effects of the invention include improved efficiency and effectiveness in removing photoresist and etch-related residues from dielectric materials.

Problems solved by technology

Highly oxidizing conditions are also generally unsuitable for use on low dielectric constant (low-k) materials.

As processes used to fabricate integrated circuits moves toward smaller and smaller dimensions and requires the use of dielectric materials having lower and lower dielectric constants, it has been found that the conventional strip plasma conditions are not suitable.

The hydrogen based plasmas without oxidizing agents, however, have very low strip rates and may not effectively remove the myriad of organic contaminants found on the wafer after etching.

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